internal Enumerator(SingleList <T> singleList)
{
_list = singleList;
_index = 0;
_currentNode = null;
_nextNode = _list.head;
}
/// <summary>
/// There are three scnarios, advancing from 0 to 1
/// From 1 to 2, 3, 5, i.e. regular
/// Reaching the end of the collection, after which reset needs to be called;
/// </summary>
/// <returns></returns>
public bool MoveNext()
{
if (_nextNode == null)
{
return(false); //End of collection reached
}
_currentNode = _nextNode;
_nextNode = _nextNode.Next;
_index++;
return(true);
}
private static IEnumerable <TResult> SelectMany <TSource, TResult>(this SingleList <TSource> list,
Func <TSource, IEnumerable <TResult> > selector)
{
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
//Create a function that just discards the index and calls the selector
Func <TSource, int, IEnumerable <TResult> > selectorWithIterator = (i, n) => selector(i);
return(SelectMany(list, selectorWithIterator));
}
public static IEnumerable <TSource> Where <TSource>(this SingleList <TSource> list,
Predicate <TSource> predicate)
{
if (predicate == null)
{
throw new ArgumentNullException(nameof(predicate));
}
//Create a function that just discards the index and calls the selector
Func <TSource, int, bool> selectorWithIterator = (item, n) => predicate(item);
return(Where(list, selectorWithIterator));
}
private static IEnumerable <TResult> SelectMany <TSource, TResult>(this SingleList <TSource> list,
Func <TSource, int, IEnumerable <TResult> > selector)
{
if (list == null)
{
throw new ArgumentNullException(nameof(list));
}
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
int i = 0;
foreach (TSource element in list)
{
foreach (TResult subElement in selector(element, i))
{
yield return(subElement);
}
i++;
}
}
public static IEnumerable <TSource> Where <TSource>(this SingleList <TSource> list,
Func <TSource, int, bool> predicate)
{
if (list == null)
{
throw new ArgumentNullException(nameof(list));
}
if (predicate == null)
{
throw new ArgumentNullException(nameof(predicate));
}
int i = 0;
foreach (TSource element in list)
{
if (predicate(element, i))
{
yield return(element);
}
i++;
}
}
public void Reset()
{
_index = 0;
_currentNode = null;
_nextNode = _list.head;
}